Knitting-machine needles were initially formed from round wire with bent tips serving as cam-follower lugs or butts. The smooth surface of these tips made it easy for them to slide along the camming surfaces of the needle lock. With the development of more sophisticated knitting machines, however, the shape of the needles and similar implements, e.g. clavettes, became more complex, requiring their manufacture by a stamping process from flat sheet steel. The lugs of such stamped workpieces, however, have rough edges which must be smoothed in order to facilitate their displacement within the needle bed and to assure precise coaction with associated cam grooves in which these lugs are usually held captive, opposite edges thereof being thus engaged during ascending and descending strokes.
Various ways have already been proposed in which such camming lugs or butts are to be machined after stamping for smoothing and truing purposes. According to one known process, the two narrow butt faces transverse to the principal dimension of the needle or clavette are beveled at angles of about 45.degree., yet this requires a succession of separate operating steps with intervening repositioning of the workpiece; such a beveling of the edges of these narrow faces, moreover, generally leaves about 40 to 50% of the original area of these faces in its prior rough condition. If that residual area is also to be machined, the number of grinding of milling operations is further increased and maintenance of the desired tolerances is exceedingly difficult; such a treatment, accordingly, is warranted only in the case of high-precision needles or the like.
Other prior proposals aim at a combined stamping and shaping operation designed to produce a desired butt profile by pressing. That technique, which is applicable only to relatively heavy workpieces, results in the formation of burrs requiring a separate trimming step for their removal.